chore: remove unused middleware files

apps/admin/middleware.js

@@ -1,14 +0,0 @@
-import { next } from '@vercel/edge';
-
-export default function middleware() {
-  return next({
-    headers: {
-      'Referrer-Policy': 'origin-when-cross-origin',
-      'X-Frame-Options': 'DENY',
-      'X-Content-Type-Options': 'nosniff',
-      'X-DNS-Prefetch-Control': 'on',
-      'Strict-Transport-Security':
-        'max-age=31536000; includeSubDomains; preload',
-    },
-  });
-}